1. Field of the Invention
The present invention relates to an organic light-emitting diode (OLED) display device.
2. Description of the Related Art
The ambient light is known to have a negative impact on the visual effect of an organic light-emitting diode display device, and the ambient light elimination design of the prior art mainly relies on adding a light absorbing layer to the display device to reduce the reflection of the incident ambient light and increase the contrast of the display device. Though the design can partially reduce the ambient light, some of the light radiated from the organic light-emitting diode device is eliminated as well. Consequently, the contrast of the display device cannot be improved significantly to enhance the visual effect.
FIG. 5A is a schematic cross-sectional view of a conventional organic light-emitting diode display device with a top-emitting surface that comprises, from bottom to top, a bottom substrate 501, a light absorbing layer 502 located on the bottom substrate 501, a reflective electrode layer 503 located on the light absorbing layer 502, an organic luminescent layer 504 located on the reflective electrode layer 503, a transparent electrode layer 505 and a transparent top substrate 506. The transparent electrode layer 505 is under the transparent top substrate 506. As the ambient light enters the display device from the top, some of the ambient light will penetrate the reflective electrode layer 503 and be absorbed by the light absorbing layer 502, thus the amount of the reflected ambient light will be less than that of the incident ambient light.
FIG. 5B is a schematic cross-sectional view of a conventional organic light-emitting diode display device with a bottom-emitting surface that comprises, from bottom to top, a transparent bottom substrate 511, a transparent electrode layer 512 located on the transparent bottom substrate 511, an organic luminescent layer 513 located on the transparent electrode layer 512, a reflective electrode layer 514 located on the organic luminescent layer 513, a light absorbing layer 515 and a top substrate 516. The light absorbing layer 515 is under the top substrate 516. When the ambient light enters the display device from the bottom, some of ambient light will penetrate the reflective electrode layer 514 and be absorbed by the light absorbing layer 515, thus the amount of the reflected ambient light will be less than that of the incident ambient light.
As described above, the light-absorbing layer 502 or 515 can partially absorb both the incident ambient light and the light radiated from the organic luminescent layer 504 or 513, thus the luminescent efficiency of the organic luminescent layer 504 or 513 will be lowered. Though the light absorbing layer 502 or 515 can reduce the negative impact caused by the ambient light, it also absorbs some of the light radiated from the organic luminescent layer 504 or 513. Consequently, the contrast of the display device cannot be significantly increased to improve the visual effect.